The UK Solar Market in 2026: Record Growth Meets Grid Constraints
The UK solar market is in an unusual position. Growth has been undeniable, but as solar has become a visible and meaningful part of the electricity system, the pace of change is forcing parts of it to adapt faster than they were designed to.
Understanding where the market goes next means looking beyond installation headlines and focusing on what recent growth has revealed about the limits of today’s infrastructure and processes.
What changed in 2025
The scale of solar’s growth became clear in 2025. BBC analysis of National Energy System Operator (NESO) data shows that solar generation increased by nearly 30% year on year, producing more than 18 terawatt hours of electricity across Great Britain and supplying over 40% of national electricity demand during short periods last summer.
This was driven by both conditions and deployment. 2025 was the UK’s sunniest year on record, and it was also a record year for new installations, with around 250,000 rooftop systems added alongside new large solar farms.
With net zero targets driving continued deployment and policies like the Future Homes Standard set to make solar a default feature of new housing, that momentum is unlikely to ease.
How growth exposed the limits of the system
One of the most immediate constraints emerging from this growth is grid capacity. Large parts of the UK distribution network were not built for high volumes of electricity flowing back into the grid, and in some regions, particularly rural areas or places with high solar uptake, there is simply not enough spare capacity to connect new systems without upgrades.
Even where connections are technically possible, the cost of reinforcing the network can be significant and difficult to predict, making project viability harder to assess, particularly for larger or multi-site developments. As deployment increases, these regional and cost-related constraints are becoming more visible and influential.
One grid, many rulebooks
Another layer of complexity comes from the way the grid is governed. Different distribution network operators have different thresholds, processes, and technical requirements. For multi-site projects and solar professionals operating across regions, these differences add time and complexity, and they make standardisation difficult.
As deployment accelerates, these variations are becoming harder to work around and more costly to ignore.
Connection queues and delays have become systemic
Capacity limits sit alongside a growing issue with connection delays. Over the past five years, the queue for grid connections has expanded dramatically, far beyond what the UK is expected to need by 2030. Projects can wait months or longer for connection offers, and even when approval is granted, physical works can push timelines out further, creating uncertainty across planning, financing, and delivery.
By the end of 2025, the scale of the problem forced action. The National Energy System Operator (NESO) confirmed a major overhaul of the grid connections process, moving away from a first-come, first-served model and towards prioritising projects that are genuinely ready to build. The intention is to clear stalled projects from the queue and provide clearer timelines, with the first offers under the new framework expected through 2026 and into 2027.
Rising system complexity
The system itself is also becoming more complex. Solar is increasingly paired with batteries, export limits are more common, and smart controls play a bigger role in meeting grid requirements. Each of these adds decisions that need to align with local network rules and connection conditions.
This increases the risk of late-stage changes if systems do not meet requirements as expected. Complexity is no longer an edge case. It is becoming the norm.
What happens next?
Taken together, these challenges do not point to a market that is slowing down. They point to a market that has grown quickly enough to push against the limits of existing infrastructure and processes.
Grid reform and renewed focus on network upgrades show that change is underway. As the UK moves through 2026, the defining question is no longer whether solar can scale. That has already been proven.
The question now is whether the system around it can adapt quickly enough to keep pace.
